Collapsible shipping and storage containers are well known in the art. Collapsibility is desirable in order to minimize the space requirements of the container when it is empty and not in use. Collapsibility improves storage and shipping options and mitigates shipping costs.
Collapsible containers typically include removable or foldable side or end walls, a base and optionally a roof. Generally, shipping containers are constructed from wood, metal or plastic parts. Metal containers are durable with high load bearing capacities, but are heavy. Plastic containers are lighter, but are not as durable, are typically much smaller in size and have reduced load bearing capacity. As a result, the storage capacity of plastic containers can be limited.
For example, a collapsible shipping container made of plastic is described in U.S. Pat. No. 4,630,746. Each part of the container has a “meshed” structure made by injection molding. The container has two opposing side walls that are inwardly foldable along a vertically hinged axis. In contrast, U.S. Pat. No. 3,870,185 teaches a collapsible plastic container having side walls that are inwardly foldable along a horizontally hinged axis. The plastic containers taught are not suitable for storage and transport of heavy loads.
A metal container having inwardly folding horizontally hinged side walls is disclosed in U.S. Pat. No. 5,190,179. The container also has end walls that pivot to within the container where they are stored when the container is collapsed. The metal container contains fork lift tines to allow for its movement when collapsed or erected. Other metal containers having similar features are disclosed in U.S. Pat. Nos. 4,577,772, 3,570,698, 4,848,618, and 4,214,669. The weight of these metal containers and their component parts often requires a forklift or other specialized equipment in order to collapse and erect the container, as well as for movement of the containers from one location to another.
In light of the above, there remains a need for a collapsible container having good load bearing properties and high storage capacity but without the added weight or corrosion problems of metal component parts.